As with most BleepingComputer tools, there is very little information available about them (hence the direct download links above), but I've seen both resolve very stubborn problems. Farbar kindly replied to my request for details about the tools by saying only a few BleepingComputer members are granted access to that information. Concern about such secretiveness is largely allayed by BleepingComputer's record of altruism (and reticence), along with the near-miracles I've seen Farbar's tools perform.